Process of condensing organic sulphur compounds



' Patented Jan. 3, 1939 PATENT OFFICE PROCESS OF CONDENSING ORGANIC SULPHUR COMPOUNDS- Joseph O. Patrick, Morrisville, 'Pa., assignor to Thiokol Corporation, ration of Delaware No Drawing.

Yardville, N. J., a corpo- Application October 4, 1937,

Serial No. 167,330

8 Claims.

This invention relates tov the production of a synthetic substance similar in some respects to rubber and having numerous properties which make it superior to rubber and capable of wide application inthe useful arts, including such uses as solvent-proof flexible conduits, oiland solvent-proof coatings for garments and gloves, gasimpervious cloth for balloons and dirigibles, as well as gas masks, all sorts of molded articles, etc.

This application is a continuation-in-part of my copending application Serial No. 733,123, filed June 29, 1934, and Serial No. 79,926, filed May 15, 1936. a

I have found that for chemical and commercial reasons there should be two stages in the production of the ultimate product, a first stage in which fan intermediate product is produced preferably by'a wet reaction, i. e., one carried out in the presence of a solvent or liquid medium and a later stage in which the intermediate product is converted to the final stage. I

The intermediate product can be produced in any desired quantities and in a predetermined condition of purity and consistency. For example, it may be a tough dough.

This intermediate product may be produced and sold in a uniform condition as raw material for a wide variety of uses. To the producer of the intermediate material, that is his final product. I-le sells it and to his vendee it is raw material. One-hundred buyers may make from this raw material as many different articles having different shapes, forms and uses.

To give an example of the manner in which I prepare the intermediate material and a typical case of themanner in which this material may be utilized by a buyer thereof, the following data is supplied:

A. PREPARATION or INTERMEDIATE MATERIAL Example 1.--3000 liters of 2 molar sodium tetrasulphide solution containing 1044 kilograms or 6000 gram mols of sodium tetrasulphide, are treated with 8 kilograms of NaOH followed by 20 kilograms of MgClaGHzO, in a reaction ves-- sel provided with coils for heating and cooling and an agitator. 6000 gram mols of ethylene difrom the washing water. It is washed and settled until free from soluble electrolytes.

The washed and purified polymer still in the form of latex is then subjected to an oxidizing treatment as follows: Sufiicient alkali is added 5 to give a pH of about 11, the temperature is raised to 200 F. and air is bubbled through the liquid for about Bhours at about 200 F. Then the oxidized polymer still in the form of latex is washed substantially free from alkali, and the 10 washed, oxidized latex is transferred to a vessel where coagulation or separation of the polymer in the form of a mass occurs. For this purpose dilute 1101 may be added until a pH of about Bis obtained shown by methyl orange. The coagu- 15 lated mass is a pale yellow, tough, highly elastic coagulum. It is washed free from acid and. then dried by masticating on hot mixing rolls. 9 About '936 kilograms of dry polymer are obtained.

This polymer is reactive and upon being com- 20 pounded and heated undergoes atransformation of which the following is a typical example, the ingredients being mixed by mastication.

Example 2 25 Kilograms Polymer as above described 100.00 Diphenyl guanidinefi .20 Zinc oxide- 10.00 Carbon black 20.00 Stearic acid .50

This mixture may be sold in bulk in the form of rubber-like sheets which may be purchased by buyers who use it for many different purposes by a simple heating operation, e., molding and 35 curing, as set forth below by way of illustration. More frequently, however, the polymer is purchased as such and the compounding or mixing, illustrated by Example 2, effected by the buyer or user thereof.

B. TRANSFORMATION or INTERMEDIATE PRODUCTS IN'ro FINAL PRonUcr Example 3.The polymer described above is placed in a moldand heated to about 290 F. for about 45 minutes. I

This step may be called curing. It comprises an oxidation in the dry or solid phase and in stead of zinc oxide other curing agents of an oxidizing character can be used. e. g., lead oxides, bismuth oxides, arsenic oxides, manganese oxides, organic perodixes, aryl and aralkyl nitro' and polynitro compounds and other oxidizing agents effective under the relatively high temperatures of the curing operation.

Attention is called to the fact that when the user of the intermediate material gets it, it has not lost its capacity to be transformed, not only in a physical sense, i. e., into difierent shapes,

etc., but also in a chemical sense. Indeed it is the chemical transformation of the intermediate product which makes it valuable in the hands of the buyer, because it is that transformation which brings out the latent or inchoate valuable properties of the ultimate article.

In other words, two chemical transformations occur, the first being the reaction or reactions by which the intermediate material is formed by the manufacturer thereof and the second the reaction or transformation which occurs when the manufacturers customer buys the intermediate material and uses it in his particular process.

I have found that there is a close correlation between the degree of success of the intermediate material in the hands of users thereof and the manner in which ,the intermediate material is made and my present invention is directed to improvements in the preparation of the intermediate material which are reflected in improved properties of the final product made therefrom.

To explain the nature of said improvement in the intermediate product and its influence on the final product, I will point out the results obtained when the step.oi' oxidation'is omitted in the procedure of Example 1.

Example 4. -Proceed as in Example 1, but omit the oxidizing step.

The intermediate polymen. thus obtained is softer and lesselastic than that obtained in Example 1. Moreover, upon compounding and then curing as in Examples 2 and 3, the eifect of omitting the oxidation is manifested by the following properties of thecured polymer, in relation to a polymer made in the same manner in all respects except that the step of oxidation in the preparation of the-intermediate polymer is included.

Cured lymer Cured polymer made thout the made with the oxidising step oxidizing step Tensile strength 600 lbs./sq. in. 1000 lbs./sq. in. Elongation 700% 500% Permanent set or deformation after elongation 20% The effect of the oxidation in the preparation of the intermediate product is thus reflected clearly in a marked improvement in the properethylene dichloride is a reaction wherein chlorine is split of! followed by condensation and may be represented as follows, R. representing can.

A. 01.11.01 NasS4=CLRB Na NaCl This continues until a long chain is built up having the formula 8 S CLRj-S. 31.3 .Na

which loses halogen and acquires 8B terminals as follows: I

in the dispersed state, in other words, the sodium polysulphlde intermediate reaction polymer was foundto be a good reducing agent and upon causing oxidation and subsequent separation and curing of the oxidized polymer, improvement in mechanical strength and elasticity was efiected V as proven by the above data.

The action of the oxidizing reagent can be explained as follows, the 1SH terminals being converted into -SNa terminals became of the strongly alkaline conditions:

terminals to hydrogen terminals and the destruction of the dispersing agent which in the example given is magnesium hydroxide.

A large variety of oxidizing agents may be used instead of air. The sodium polysulphlde-ethylene dichloride reaction product polymer, is an excellent reducing agent in alkaline solution, a strong reducing agent, as it must obviously be in order to be oxidized by merely blowing air through its alkaline solution. With this knowledge, the chemist may employ any oxidising agent efi'ective in alkaline solution, e. g., hypohalites, hydrogen peroxide, metallic peroxides, perborates, etc.

Attention is directed to the fact that the oxidation step is preferably carried out under definite'ly alkaline conditions, as indicated in Example 1 by a pH of about 11 It has been found that the oxidation is very favorably infiuenced by said alkaline condition.

01. course, consideration of cost places a commercial limit and in seeking a cheap oxidizing agent, it was found that alkaline polysulphides play a dual role provided that enough is used in phide to about 1 mol of ethylene dichloride, then a part of the alkaline polysulphide, i. e., about 1 mol, acts to introduce the polysulphur radicals into the ethylene radical as in Equations A to E above, whereby the initial polymer is formed as a conjugated polysulphur complex as shown, and the other part acts as an oxidizing-agent as in Equation F above. In playing its oxidizing role, it is the sulphur of the inorganic polysulphide which acts as the oxidizing agent, thus:

2NaS.RS .RS .R.SNa-|-S NaS.RS .RS .R.S.S.R.RS .RS .NaS+NaS' Thus, by employing about 2 mols of sodium polysulphide to 1 mol of ethylene dichloride instead of the equimolecularflproportions of Example 1, a polymer can be obtained which upon subsequent curing, produces a cured product having' mechanicahstrength and other properties similar to that obtained from the product of Example 1, even though no air is blown through the suspension. reaction nevertheless, the polysulphide playing two diiferent roles in the respective stages. This is illustrated by the following examples:

Example 5.-3000 liters of 2 molar sodium tetrasulphide solution containing 6000 gram mols of the tetrasulphide are treated with 8 kilograms of NaOH followed by 20 kilograms of MgClzGHzO in a reaction vessel provided with coils for heating and cooling and an agitator. Then 3000 mols or about 297 kilograms ofethylene dichloride are gradually added during about 3 hours at a temperature of about F. After all' the ethylene dichloride has been added the temperature is raised to about 200 F. and maintained there for about 3 hours.

This 3 hour heating is comparable with the air-blowing step of Example 1, the additional polysulphide acting as an oxidizing agent, i' e., the first step is the formation of the initial polymer consisting of a conjugated chain of polysulphur complexes alternating with ethylene radicals and the second stage is the oxidation of this polymer. polysulphide plays different roles.

The polymer thus obtained is in the formof a latex which is washed and coagulated as in Example l, and compounded and cured as in Examples 2 and 3, and the cured polymer is found to have properties substantially identical with those of the cured polymer obtained from the intermediate polymer where oxidation was effected by a current of air Example 1).

The reaction of the sodium-polysulphide with the ethylene dichloride is one wherein the chlorine is removed and its place taken by a polysulphur group. See Equations A to E- above. There is no question that this occurs because sodium chloride is one of the by-products. Instead of chlorine, other substituents may be employed, including bromine, iodine, nitrate, sulphate, carbonate,, acetate, propionate, etc., in fact any substituent which is split ofl during the reaction.

Ethylene dichloride has been used as an illustrative example, but the invention is not at all limited to that compound and includes a large number of compounds where there is a substituent attached to each of at least two different carbon atoms which substituent is split ofi during The reaction is however a 2-stage In these two stages the sodium the reaction as shown in the list as set forth below. 'Any of the compounds of this list can be substituted for the ethylene dichloride of .Examples 1 and 5, in the respective molecular proportions therein set forth. In this list, the symhols X and X represent, respectively, a substituent on each of two difierent carbon atoms which substituent is split off during the reaction.

' xicnmx' where a may be 1 to 20 or-rnore CH3.(|JH.(|JH.CH3

2,3 disubs tituted butane CH3.CH.CH3

2,3 disubstituted propane QHa.CH2.( 3H.C-Hz(I3H.CHz.CHs

3 ,5 disubstituted he ptane xomonon x out Disuhstituted isobutauo I X.C2H4O.C2H4.O.C2H4.X'

. Disubstituted ethoxy ethyl ether X.CH2.0.CH2.X

Disubstituted methyl ether XC2H4.S.C2H4X' Disubstituted thio ethyl ether xczmo'cnzx' Disubstituted methyl ethyl ether- C-Hs xonzo.oH,.c.cHi.o.oH2.x'

CH: Disubstituted l ,3 methoxy 2,3 'dimethyl propane J X.CH2.S.CH2.X'

Disuhstituted thio methyl ether X.CH2.CH2.CHz.O.CI-I2.O.CH2.CHz.CHz.X'

I Dlsubstituted dipiopyl fomal I X.CH2.CH2.O.CH2.O.CH2.CH2.X'

Disubstituted diethyl formal XCH2OCHzCH.O CH;

,2, Disubstitutcd dimethoxy ethane Disubstituted para diethoxy benzene xomoomcmocrnx' Disubstituted dimethoxy ethane X.CH2.CH2.CH2.S.CH2.CH2.CH2.X'

Disubstituted dipropyl thio ether XCHrCHz-O-fi-(lCHTCHrX' Disubstituted diethyl carbonate X.CH2.CH2.SO2.CH2.CH2.X'

Disubstituted diethyl sulphone xcm.cn=cn.cmx'

Disubstituted butane 2, 3

Disubstitutod 3 tolyl propane 2, 3

Disubstituted para xylene Disubstituted para ethyl butyl benzene It is of great advantage to prepare the intermediate product in the form of a dispersion. This permits the substantially complete removal of by-products as by washing, prior to coagulation, so that a purified intermediate product is obtained; Not only that, but in its dispersed form, the polymer, particularly in alkaline solution, is susceptible of oxidation as set forth, to

may be overlapping. The initial reaction of the polysulphide is one of chain formation. The subsequent reaction, whether caused by polysulphides or other oxidizing agent isa lengthening of thechain or chains already formed.

I claim:

l. The procas which comprises providing an organic compound havinga substituent joined to each of two different carbon atoms which substituent is split oil during the reaction, reactin this with an alkaline polysulphide, oxidizing the product, and obtaining a polymer in intermediate potentially reactive form capable of being cured by a subsequent heat treatment. I

2. The process which comprises providing an organic compound having a halogen joined to each of two different carbon atoms, reacting this with an alkaline polysulphide, oxidizing the product, and obtaining a polymer in intermediate potentially reactive form capable of beins cured by a subsequent heat treatment.

3. The process which comprises providing an organic compound having a substituent Joined to each of 7 two different carbon atoms which substituent is split off during the reaction; reacting this with an alkaline polysulphide in a dispersion medum and obtaining a polymer in dispersed form oxidizing the polymer while still in dispersed form; and separating the polymer in an intermediate potentially reactive form capable of being cured by a subsequent heat treatment.

4. The process which comprises providing an.

organic compound having a substituent joined to each of two diflerent carbon atoms which substituent is split oi! during the reaction, reacting this with an alkaline polysulphide in a dispersion medium and obtaining a polymer in dispersed form; applying an oxidizing agent to the dispersion under alkaline conditions; and obtaining a polymer in intermediate potentially reactive form capable of being cured by a subsequentheat treatmnt.

' 5. The process which comprises providing an organic compound having a substituent joined to each of two diiferent carbon atoms which substituent is split off during the reaction, reacting this with an alkaline polysulphide and oxidizing the product, in an alkaline dispersion medium in the presence of a dispersion agent; obtaining a polymer in the form of a latex-like liquid, and separating said polymer from said liquid in intermediate potentially reactive form capable of being cured by a subsequent heat treatment.

6. The process which comprises providing organic compound having a substituent joined to each of two different carbon atoms which substituent is split off during the reaction; reacting this with a quantity of alkaline polysulphide sufllcient to cause the formation of an organic polymer and an additional quantity of polysulphide to oxidize said polymer; and obtaining a polymer in intermediate form, capable of being cured by a subsequent heat treatment.

7. A potentially reactive intermediate polysulv phide polymer, capable of being cured when heated, and resulting from the action of an oxidizing agent on the reaction product of an alkaline polysulphide with an organic compound having a substituent on each of two diflerent carbon atoms which substituent is split oi! during the reaction.

8. A potentially reactive intermediate polysul-- phide polymer, capable of being cured when heated, and resulting from the process which comprises providing an organic compound having a substituent joined to each of two different carbon atoms which substituent is split oi! during the reaction; reacting this with a quantity of alkaline polysulphidesuflicient to cause the formation of an organic polymer and an additional quantity of polysulphide to oxidize said polymer.

' JOSEPH C. PATRICK. 

